Is it good for AI.SE to overlap significantly with other SE sites? Should the amount overlap be reduced?

Question

Proposal: Artificial Intelligence

I have a few concerns about the AI proposal.

1. The site content doesn't match the description.

The AI.SE proposal has the description

Beta Q&A site for conceptual questions about life and challenges in a world where "cognitive" functions can be mimicked in purely digital environment.

which does not really describe the kinds of questions that the AI.SE website receives. Instead of being about "life and challenges in a world where "cognitive" functions can be mimicked in a purely digital environment", the AI.SE website attracts many questions about how to implement intelligent agents, such as machine learning, neural networks, and reinforcement learning. A question about how to build a neural network to achieve a specific task, or how U-Net works, or how to express a neural network using linear algebra, is very different from a conceptual question about life in a world where cognitive functions are mimicked in a purely digital environment.

2. There is a large overlap with stats.SE

I appreciate that the popular imagination does not see a strong connection between "boring, old statistics" (p-value and t-tests and regressions) and "new, sexy, cutting-edge" artificial intelligence, but the fact is neural networks are a topic in statistics, broadly conceived. The stats.SE website already has deep coverage of machine learning and neural networks. Machine learning is even listed as a topic that users can ask questions about in the Stats.SE help page.

A number of the AI.SE topics on these questions are perfectly on-topic on stats.SE and are already answered.

The large overlap with stats.SE seems to cannibalize and existing website, which is undesirable. The SE blog has written about this in the past.:

Area 51 was always envisioned as a tool for broadening our scope — for creating new sites serving new topics and answering questions that were previously considered off-topic on our existing sites. Area 51 was never intended as a tool for creating overlapping sub-sites that would cannibalize users from our existing sites!

The problem of site overlap could have been avoided. A hypothetical Area 51 proposal for a website about the philosophical and conceptual components of AI could have been written. If this proposal excludes statistical topics in AI, this website would not overlap with stats.SE. Or, alternatively, the existing AI.SE website could conform to the description above. But that's not what's happened, and now AI.SE has a lot of overlap with stats.SE.

As moderator and experienced user of stats.SE, and as a professional who focuses on machine learning and neural networks, I can confidently say that a large portion of the questions on the AI.SE website are on-topic on stats.SE.

Here are some examples of overlap. I hope this makes it clear that the AI.SE site and stats.SE site have a lot of material in common. Both sites have thousands of questions, and it takes time to correlate content between them.

1. AI.SE has a question What is the use of convolutional layer in expansion path of U-Net?

This question is on-topic on stats.SE because it asks how a specific neural network works. We have 85 questions about U-Nets on stats.SE. https://stats.stackexchange.com/search?q=u-net

2. AI.SE has the question Correct way to work with both categorical and continuous features together This question is already answered on stats.SE, in several forms:

• https://stats.stackexchange.com/questions/479433/combining-categorical-and-continuous-features-for-neural-networks
• https://stats.stackexchange.com/questions/306610/neural-network-mlp-for-regression-with-3-continuous-features-1-categorical
• https://stats.stackexchange.com/questions/139129/how-to-recode-categorical-variable-into-numerical-variable-when-using-svm-or-neu

3. AI.SE has the question How to select number of hidden layers and number of memory cells in an LSTM?

• https://stats.stackexchange.com/questions/286713/optimum-number-of-epochs-and-neurons-for-an-lstm-network

4. What is the purpose of an activation function in neural networks? Stats.SE has several variations on this.

• https://stats.stackexchange.com/questions/228296/what-is-the-purpose-of-a-neural-network-activation-function
• https://stats.stackexchange.com/questions/333700/to-what-exactly-does-the-term-activations-refer-in-neural-networks

5. How is a deep neural network different from other neural networks?

• https://stats.stackexchange.com/questions/222883/why-are-neural-networks-becoming-deeper-but-not-wider

3. The overlap is contentious and confusing.

And the issue of overlap between AI.SE and Stats.SE has arisen several times on stats.SE. Speaking for myself, I am somewhat perplex that another website has been created which, in effect, overlaps with much of the stats.SE content.

• https://stats.meta.stackexchange.com/questions/5514/overlap-with-ai-stackexchange-and-datascience-stackexchange
• https://stats.meta.stackexchange.com/questions/5573/questions-on-reinforcement-learning-topics-would-be-better-suited-for-ai-stack-e?noredirect=1&lq=1
• https://stats.meta.stackexchange.com/questions/6050/should-stats-se-encourage-rl-questions-to-be-asked-on-ai-se
• https://stats.meta.stackexchange.com/questions/4243/after-data-science-se-artificial-intelligence-se
• https://stats.meta.stackexchange.com/questions/2094/where-should-i-ask-a-question-about-artificial-intelligence
• https://stats.meta.stackexchange.com/questions/5913/can-we-ask-questions-related-to-deep-learning-ai/5914#5914

4. Should machine learning questions on AI.SE be part of an existing site, or its own site?

The Area 51 FAQ provides a general rubric for answering this. I've substituted in X=AI.SE and Y=Stats.SE to make the general formula in the FAQ easier to read, and revised the focus of the general formula to the particulars of the topics in question. I know that, in this edited form, this is not the Official Area 51 rubric; however, I think it is illustrative of the core problem, which is that the scope of AI.SE is so expansive that it overlaps with existing websites.

In general, if a site makes sense as part of a bigger site, it's better to have one big site than a bunch of little niche sites. Machine learning questions on AI.SE should be subsumed by Stats.SE if:

1. Almost all machine learning questions on AI.SE questions are on-topic for site Stats.SE

This criterion is established in header 2 on this post.

2. If Stats.SE already exists, it already has a tag for machine learning, and nobody is complaining

This criterion is established by the meta threads on stats.SE about machine learning as a topic make it clear that stats.SE welcomes statistical questions about machine learning. This is header 3 of this post.

3. You're not creating such a big group that you don't have enough experts to answer all possible questions

This one is hard to judge. The statistics reported on the AI.SE Area 51 page are mostly good, but the answer rate and number of daily questions need some work. This answer from DuttaA on Meta.SE describes a need on AI.SE for more experts:

Our site is very small and non-rewarding, there have been multiple experts who have came and gone (but hangs out in other SE sites). So this has resulted in a severe lack of community moderation.

Returning to the FAQ's criteria,

4. There's a high probability that users of site Stats.SE would enjoy seeing the occasional question about machine learning.

Stats.SE has tens of thousands of posts about machine learning and neural networks. These questions are not occasional. Stats.SE has occasional posts about the history of these topics.

Stast.SE does not have many questions at all about philosophy of intelligence, theories about general intelligence in digital systems, or "conceptual questions about life and challenges in a world where "cognitive" functions can be mimicked in purely digital environment." Such questions are likely off-topic on Stats.SE but they may be on-topic on a Stack Exchange site other than AI.SE.

The AI.SE website, as it exists now, does not seem to meet the criteria required to stand on its own.

What to do?

I don't know what can be done, at this juncture, since the AI.SE website is about 4 years old. In all honesty, I'm not familiar with how Area 51 works, in specific terms.

It's clear that the site has evolved over that time, since its content and description differ. But I am concerned that right now, AI.SE and Stats.SE are a Venn diagram with an enormous overlap, and this seems to harm both websites.

The overlap isn't necessary. The AI.SE description is very different from the AI.SE content that exists today. An AI.SE website which grapples with "conceptual questions about life and challenges in a world where cognitive functions can be mimicked in a purely digital environment" is a novel and intriguing SE website proposal. I think it could be a nice community.

Here's another way to frame the issue. Suppose some new, unnamed site started with a very clear, non-overlapping description that AI.SE used. Then this unnamed site extended that description to also include the kinds of questions about theories of intelligent systems, pathfinding problems/algorithms, tree search or graph search algorithms and logic-based AI approaches. That would seem to be fine because there's still no overlap with stats.SE, and these questions all have a coherent home.

But what has happened instead is that the AI.SE proposal defined itself in terms that clearly have no overlap, and on the basis of this description, this website was able to get launched via the Area 51 process. Then, the AI.SE website changed its topics to have large overlap with existing websites, such as stats.SE. The effect of this metamorphosis is that there's a lot of confusion and duplication of effort, as well as a fracturing of expertise across different websites.

Answer 1

In general, if a site makes sense as part of a bigger site, it's better to have one big site than a bunch of little niche sites. AI.SE should be subsumed by Stats.SE if:

1. Almost all AI.SE questions are on-topic for site Stats.SE

This criterion is established in header 2 on this post.

No, this has not been established in header 2 of your post. You have established that there exists an overlap -- probably a relatively large one, but I would certainly not qualify it as "almost all". Examples provided on this blog post include a "Guitars" site being subsumed by "Musical Practice and Performance". Yes, that would be an example where really almost every single question on-topic for Guitars would also be on-topic for Musical Practice and Performance. Not just a reasonably large amount, but literally almost all. That's not what we have here. Some examples of AI topics that I would guess would not be on-topic on stats.se would be:

1. Pathfinding problems/algorithms
2. Many kinds of tree search or graph search or other search algorithms
3. Logic-based AI approaches
4. Probably many other things I can't think of right now, nbro's answer also includes some

Furthermore, I imagine that hybrids of any of the above in combination with machine learning might also be questionable on Stats.SE? Not 100% sure about this, but I imagine it would be a gray area and at some point require so much expertise of the non-stats-based AI components of a hybrid that it would become more suitable for AI.SE.

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2. If Stats.SE already exists, it already has a tag for AI, and nobody is complaining

This criterion is established by the meta threads on stats.SE about AI as a topic make it clear that stats.SE welcomes statistical questions about AI. This is header 3 of this post.

No, again this criterion has not been established. You're again just focusing on statistical questions about AI, but that's definitely not all that AI is about. Stats.SE does indeed have an artificial-intelligence tag, but it sees relatively little use and it's not one that noone's complaining about (or at least not one that noone raises any questions about, "complaining" may be too strong a word). See https://stats.meta.stackexchange.com/q/4257/144483 and https://stats.meta.stackexchange.com/q/5547/144483. You have in fact written answers to both of those questions yourself where you point to the non-stats-based topics that are also relevant to AI, and that those should probably be redirected to AI.SE, so clearly there's an area there in AI.SE that should not be subsumed by Stats.SE.

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4. There's a high probability that users of site Stats.SE would enjoy seeing the occasional question about AI.

Stats.SE has tens of thousands of posts about machine learning and neural networks. These questions are not occasional. Stats.SE has occasional posts about the history of these topics.

Again, this criterion is clearly also not satisfied. I guess the wording of "would enjoy seeing the occasional question about AI" is not entirely clear though. My understanding is that it should be read as "would enjoy seeing the occasional question about any topic that is on-topic in AI", as opposed to "would enjoy seeing the occasional question about some topics that are on-topic in AI". I'm sure that Stats.SE would enjoy seeing occasional questions about some AI topics (like machine learning), but would not enjoy seeing a wide variety of other AI topics (pathfinding, tree search, logic stuff, ...).

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So, to me it is very clear that Stats.SE cannot subsume AI.SE in its entirety, at least three out of four of the criteria (which must all be satisfied) are not satisfied.

I suppose you could raise the question if you want whether Stats.SE should subsume only some parts of AI.SE. Should anything that would be on-topic on Stats.SE be redirected to Stats.SE, and everything else just stay on AI.SE?

For me, the answer to that would again be a very clear no. At least some of the subsumption criteria would hold here, but it would be incredibly confusing and harmful for all visitors. An AI.SE site where logic stuff, tree search, pathfinding, expert systems, etc. are all on-topic, but one of the most "hyped" current topics of AI (Machine Learning) is not on-topic? That would probably be the most confusing site on the entire network, that's an indefensible stance.

Personally, I also don't see what the problem in having some overlap is. There is partial overlap in topics between the two sites, but there are also very clear distinct needs for each of them that cannot be satisfied by the other. So why not just let both of them exist, and if people have questions that could be on-topic on either one, let them pick where they want to post it.

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Finally, from somewhere close to the top of this blog post, I'd like to point out this quote:

3. Easier to remember and share. Stack Overflow grew to be successful because programmers told each other, “try asking on Stack Overflow.” If we had made 2500 different sites for every possible niche programming technology, nobody could have known about all of them.

Of course this quote is actually about why they just have stackoverflow.com instead of distinct java.com, python.com c++.com, etc. websites, so it's a bit of a different discussion, but it still shows that being "easy to remember and share" is considered to be valuable and relevant. To me, personally, Stats.SE has never been that, especially not when it comes to AI stuff. I think the AI.SE "brand name" has significant value here.

Many students around the world these days learn about Machine Learning because they're enrolled in Artificial Intelligence programs (not all of them, there are probably also lots of other names, but some of them at least -- my past self included). There are journals and conferences on Artificial Intelligence, which include ML stuff (as well as the other topics) in their scope. I consider myself an Artificial Intelligence researcher, and in my research I dabble in ML as well as other AI topics. I consider myself an expert and feel comfortable answering many questions on AI.SE. However, I am certainly not a trained statistician, and I don't consider myself a statistics researcher or expert, and would not feel comfortable answering many questions on a Stats.SE site (except when I specifically search for the handful of tags that I really feel like I can contribute to).

If I were to have a question about any of the topics I work in on a daily basis, my first instinct would almost never be to visit a somewhat confusingly-named "Cross Validated" site (which then doesn't have cv, but stats, in its URL). I'm doing AI stuff, so I would search for an AI-based Q&A site. Except of course when in my research I run into questions about statistical significance testing or that sort of stuff -- that's when my first instinct is to click on Stats.SE results in my google search.